1. Field of the Invention
The field of art to which this invention pertains is the catalytic conversion of hydrocarbons. More particularly, the present invention relates to a process which is useful for performing the hydrocracking of hydrocarbons. This invention also relates to hydrocarbon conversion catalysts and their method of manufacture.
2. Description of the Prior Art
The hydrocracking of hydrocarbons by catalytic means is old and well known in the prior art. Hydrocracking of hydrocarbon oil, which may be high-boiling fractions, such as for example reduced crudes, gas oils, topped crudes, shale oil, coal extract and tar sand extract, generally is performed at relatively high temperatures and pressures of the order of 500.degree. F. and 500 psig and upward. Catalysts for the hydrocracking of hydrocarbons are generally moderate to strong hydrogenation catalysts.
The prior art hydrocracking catalysts will typically comprise one or more components selected from silica, alumina, silica-alumina, crystalline aluminosilicate, or other refractory inorganic oxide and at least one metal component from Group VIB or Group VIII. Hydrocracking catalysts containing alumina and a crystalline aluminosilicate, as well as alumina and silica, have been shown to be particularly effective in the hydrocarbon hydrocracking process. One or more hydrogenation components have been selected by the prior art to serve as the hydrogenation component in hydroconversion catalysts. The prior art has broadly taught that hydrogenation components may be selected from at least the following metals: iron, cobalt, nickel, ruthenium, rhodium, palladium, osmium, iridium, platinum, chromium, molybdenum, tungsten, vanadium, niobium and tantalum. The prior art has also taught that a preferred component of hydrocracking catalyst is a crystalline aluminosilicate (CAS) and may be selected from at least the following crystalline aluminosilicates: X zeolite, Y zeolite, mordenite, etc. Other preferred components of hydrocracking catalyst are amorphous silica and alumina, amorphous silica-alumina and cogelled silica-alumina.
In U.S. Pat. No. 3,956,104 (Hilfman et al.), a preferred hydrocracking catalyst contained molybdenum and nickel. In U.S. Pat. No. 3,931,048 (Hilfman et al.), a preferred hydrocracking catalyst comprises nickel, tungsten and a silica-alumina carrier material. U.S. Pat. No. 3,184,404 (Flinn et al.) teaches the combination of tungsten and a metal selected from Group VIII of the Periodic Table of the Elements on an alumina support as an effective hydrocracking catalyst. The hereinabove mentioned patents relate to hydrocracking catalysts which are associated with refractory inorganic oxide support materials and which patents provide examples of some of the prior art catalysts.
It is generally recognized that catalysis is a mechanism particularly noted for its unpredictable nature. Minor variations in a method of manufacture often result in an unexpected improvement in the catalyst product with respect to a given hydrocarbon conversion reaction. The improvement may be the result of an undetermined alteration in the physical character and/or composition of the catalyst product difficult to define and apparent only as a result of the unexpected improvement in the catalyst activity, selectivity and/or stability.